Diet soda may do more harm than good

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Photos:Where do we stand on artificial sweeteners?

Health effects of artificial sweeteners: Where do we stand? – Millions of Americans use tabletop artificial sweeteners each day. Millions more eat foods sweetened with combinations of the fake stuff. But just how healthy are they?

The 137-year history of these nonnutritive options is full of health concerns, both overblown and real.

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Photos:Where do we stand on artificial sweeteners?

1879: First artificial sweetener, saccharin, is finger lickin' good-for-you – Oddly enough, it was bad laboratory technique -- combined with poor hygiene -- that led to the discovery of several of today's top artificial sweeteners.

Russian chemist Constantin Fahlberg was eating dinner when he made an amazing discovery: The roll he'd just bitten into tasted extremely sweet. Realizing the sugary, metallic taste had come from his own hands, he rushed back to the lab to find the source. After tasting everything in sight -- not exactly good lab safety protocol -- he discovered the sweetness came from an accidental chemical reaction between coal tar derivatives (yum!), producing benzoic sulfinide.

That's one version of the story. Another account says Fahlberg's American boss, Dr. Ira Remsen, was the diner who forgot to wash up before eating. Regardless, it was Fahlberg who applied for a patent for saccharin as an inexpensive sugar substitute

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Photos:Where do we stand on artificial sweeteners?

1900: Poison Squad eats food heavily laced with saccharin – In the early 1900s, a group of civil servants was given free room and board if the men would eat food heavily laced with widely used chemical preservatives, including borax and saccharin.

They were required to weigh in and take their vital signs before each meal and report any physical reactions. They also had to supply their urine and feces for analysis.

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Photos:Where do we stand on artificial sweeteners?

1908: Weight-watching President Roosevelt keeps saccharin from being banned – The "Poison Squad' was the brainchild of Dr. Harvey Wiley, chief of the U.S. Department of Agriculture's chemical division. He strongly believed that saccharin was a danger to health and took his case to President Theodore Roosevelt.

But Roosevelt would have none of it, as he was using saccharin to manage his weight. Wiley describes the President's reaction in his autobiography: "'You say saccharin is injurious to health? Why, Doctor Rixey gives it to me every day. Anybody who says saccharin is injurious to health is an idiot.'"

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Photos:Where do we stand on artificial sweeteners?

1970: Cyclamate will give you cancer, if you are a lab rat – The 1970s saw a number of studies of lab rats fed high doses of saccharin and a newly discovered sweetener, cyclamate. Cyclamate was linked to bladder, urinary, lung, stomach and reproductive tumors in the rodents.

While later studies found the bladder issues were due to parasites and other urinary peculiarities unique to rats, the damage was done. The FDA banned cyclamate in 1970. While 100 other countries have declared cyclamate safe and use it in their food, the FDA ban remains in the United States.

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1977: Saccharin gets a warning label – Because saccharin had such a bitter, metallic aftertaste, cyclamate was added to the tabletop version, Sweet'N Low, in a 10-1 ratio. When cyclamate was banned, the makers of Sweet'N Low quickly switched to an all-saccharin version, but suspicions remained about saccharin's role as a carcinogen in rats.

In 1977 Congress decreed that any food sweetened with saccharin must carry a scary warning label: "Use of this product may be hazardous to your health. This product contains saccharin which has been determined to cause cancer in laboratory animals."

1965: Another accidental find, in many ways 'Equal' to its predecessors – Chemist James M. Schlatter was looking for an anti-ulcer drug when he stumbled upon the sweet taste of aspartame by (you guessed it) licking his finger. A mix of aspartic acid and phenylalanine, two naturally occurring amino acids, aspartame entered the growing artificial sweetener market in 1973. Today it's sold as Equal, Nutrasweet or Sugar Twin.

Unlike the other artificial sweeteners, which are usually excreted unchanged, aspartame can be metabolized, so it does have minimal calories (about 4 per gram). It also has some known uncommon health concerns. It should not be used by anyone with the genetic disorder phenylketonuria or certain rare liver disorders, or pregnant women with high levels of phenylalanine in their blood, because it doesn't metabolize properly in those individuals. The FDA requires any food made with aspartame to put that restriction on the label.

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1976: Another brave chemist tastes his delicious experiment – Scientists were working with a chlorinated sugar compound in 1976 when one of the researchers decided to (what else?) taste it. Sucralose was born. It's made by replacing three hydrogen and oxygen atoms in sucrose with chlorine atoms, making it about 600 times sweeter than sugar.

Today we know this chlorine-based sugar derivative as Splenda. As the most heat-stable of all of the artificial sweeteners, it's popular with food manufacturers.

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2005: Diet sodas cause weight gain – By 2005, millions of people were using artificial sweeteners for weight control. So it was a shock when researchers at the University of Texas found that conventional wisdom was wrong, when they analyzed eight years of data from the San Antonio Heart Study. The more diet sodas a person drank, the more likely he or she was to gain weight.

To this day, no one knows why. Was it due to the artificial sweetener? Was it something else in the soda? Does drinking a diet soda make it more likely a person might order a double size burger and fries?

Oh, and for the record, a 2013 review says there is still evidence that diet soda helps with weight loss.

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2012: Artificial sweetners probably safe, but some lingering health concerns – Studying the effects of specific artificial sweeteners is a challenge in today's world, as many soda and food manufacturers create mixtures of sweeteners to mimic sugar and make their products taste unique. So it's hard to tease out which of the sweeteners might be a problem.

(CNN)Diet soda drinkers have the same health issues as those who drink regular soda, according to a report published Wednesday.

Purdue University researchers reviewed a dozen studies published in the past five years that examined the relationship between consuming diet soda and health outcomes for the report, published as an opinion piece in the journal Trends in Endocrinology & Metabolism. They say they were "shocked" by the results.

"Honestly, I thought that diet soda would be marginally better compared to regular soda in terms of health," said Susan Swithers, the author of this opinion piece and a behavioral neuroscientist and professor of psychological sciences. "But in reality, it has a counterintuitive effect."

Artificial sweeteners in diet soda fulfill a person's craving for a sweet taste without the calories. But that's the problem, according to researchers. Think of it like crying wolf.

Fake sugar teases your body by pretending to give it real food. But when your body doesn't get the things it expects to get, it becomes confused on how to respond.

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"You've messed up the whole system, so when you consume real sugar, your body doesn't know if it should try to process it because it's been tricked by the fake sugar so many times," Swithers said.

On a physiological level, this means when diet soda drinkers consume real sugar, the body doesn't release the hormone that regulates blood sugar and blood pressure.

Diet soda drinkers also tend to pack on more pounds than those who don't, the report says.

"The taste of sweet does cause the release of insulin, which lowers blood sugar, and if carbohydrates are not consumed, it causes a drop in blood sugar, which triggers hunger and cravings for sugar," said CNN diet and fitness expert Dr. Melina Jampolis.

The artificial sweeteners also dampen the "reward center" in your brain, which may lead you to indulge more calorie-rich, sweet-tasting food, according to the report.

The American Beverage Association says the report was "an opinion piece, not a scientific study."

"Low-calorie sweeteners are some of the most studied and reviewed ingredients in the food supply today," the association said in a statement. "They are safe and an effective tool in weight loss and weight management, according to decades of scientific research and regulatory agencies around the globe."

Diet soda's negative effects are not just linked to weight gain, however, the report says.

It found that diet soda drinkers who maintained a healthy weight range still had a significantly increased risk of the top three killers in the United States: diabetes, heart disease and stroke.

"We've gotten to a place where it is normal to drink diet soda because people have the false impression that it is healthier than indulging in a regular soda," Swithers said. "But research is now very clear that we need to also be mindful of how much fake sugar they are consuming."

All of them are chemicals. "Saccharin was one of the first commercially available artificially sweeteners, and it's actually a derivative of tar," Swithers said.

Natural sweeteners like Stevia -- which has no calories and is 250 times sweeter than regular sugar -- are not a chemical but are still a processed extract of a natural plant and increase your health risks similar to artificial sweeteners.

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"Just because something is natural does not always mean that it is safer," Jampolis said.

There more studies and research that need to be done, but in the meantime, experts say, limit consumption.

"No one is saying cut it out completely," Swithers said. "But diet soda should be a treat or indulgence just like your favorite candy, not an everyday thing."